Honing machine for bearing rings and method for feeding such a machine with bearing rings

ABSTRACT

A honing machine for bearing rings includes a frame, a honing tool, a honing station for holding a bearing ring in position with respect to the honing tool, the honing station includes a work piece holder with a concave surface equipped with at least one pad for supporting a bearing ring. The work piece holder is equipped with a damper movable between a first active configuration and a second passive configuration. In the first active configuration, the damper protrudes on a path of a bearing ring moving towards the work piece holder in the honing station. In the second passive configuration, the damper is out of reach of a bearing ring in the honing station.

CROSS REFERENCE TO RELATED APPLICATION

This is a Non-Provisional Patent Application, filed under the ParisConvention, claiming the benefit of Europe (EP) Patent ApplicationNumber 15305316.0, filed on 2 Mar. 2015 (02.03.2015), which isincorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a honing machine which can be used for ahoning process on bearing rings. This invention also relates to a methodfor feeding a honing machine with bearing rings.

BACKGROUND OF THE INVENTION

In the field of bearings manufacturing, it is known to use a honingmachine provided with a honing tool or “honing stone” which is broughtinto contact with a raceway of a bearing ring, in order to improve itsfinish. During a honing process, each bearing ring is held in a honingstation and driven in rotation with respect to the honing tool whichremains stationary. A bearing ring present in the honing station must besupported by a work piece holder which is generally provided with padsmounted on a concave surface which is shaped according to the dimensionsof the bearing rings to be processed in the honing machine. The pads areused to precisely center each bearing ring with respect to a rotationaxis of a rotatable member which drives the bearing ring in rotationwith respect to the honing stone. Thus, it is essential that the padsare correctly positioned with respect to the rotation axis.

When the honing station is fed by gravity with bearing rings, pads madeof a hard material are difficult to use, since there exists a risk ofbreakage of the pads, upon the impact of a ring entering the honingstation. An alternative consists in using relatively soft pads, such aspads made of a synthetic material. A drawback of this approach is thatsuch pads tend to wear off, so that they do not allow a precisepositioning of the bearing rings with respect to the rotation axis.

Moreover, a bearing manufacturer generally offers a range of bearingswhose inner and outer rings have different dimensions. Thus, bearingrings with different dimensions have to be successively processed on ahoning machine. When it is needed to switch the honing machine from aconfiguration where it handles a first type of bearing rings to anotherconfiguration where it handles a second type of rings, the work pieceholder has to be changed and carefully positioned with respect to aframe of the honing machine. Because of the limitations of the currentwork piece holders, such an operation implies that a dummy bearing ringmust be located in the honing station and manually centered on therotation axis in order to be used as a reference for the pads of a newwork piece holder to be installed in the honing station. Thiscomplicated setting operation is time consuming and requires a highlyqualified manpower.

SUMMARY OF THE INVENTION

The present invention aims at solving these problems with a new honingmachine having a work piece holder which can be provided with hard andlong-lasting pads, with a low breakage risk.

To this end, the invention concerns a honing machine for bearing rings,this machine including a frame, a honing tool, a honing station forholding a bearing ring in position with respect to the honing tool, thehoning station including a work piece holder with a concave surfaceequipped with at least one pad for supporting a bearing ring. Accordingto the invention, the work piece holder is equipped with a dampermovable between a first active configuration, where it protrudes on apath of a bearing ring moving towards the work piece holder in thehoning station, and a second passive configuration, where it is out ofreach of a bearing ring in the honing station.

Thanks to the invention, the damper is capable of preventing a directimpact between a bearing ring entering the honing station and the padsof the work piece holder. Since the pads are not subjected to a largenumber of impacts, they can be made in a hard material, which allowsthem not to wear off as quickly as pads made of a synthetic material.Since the pads do not wear off, their dimensions remain constant and thework piece holder can be installed within the honing station withouthaving to use a dummy bearing ring.

According to further aspects of the invention which are advantageous butnot compulsory, such a honing machine can incorporate one or several ofthe following features:

-   -   Each pad of the work piece holder is coated with a high        stiffness material, in particular with a layer of        polycrystalline diamond.    -   The damper includes a pin, which is movable in translation along        a vertical axis, and damping means for braking a vertical        downward displacement of the pin.    -   The pin is movable along the vertical axis between a first        position, where it protrudes upwardly with respect to an        adjacent pad of the work piece holder, and a second position,        where an upper surface of the pin is below an upper surface of        the adjacent pad.    -   The damping means include a rotatable shaft movable in rotation        around its longitudinal axis, between a first angular position        where it interacts with a vertical downward movement of the pin        between its first and second positions and a second angular        position where the shaft is out of reach of the pin, and a gas        cylinder for moving the shaft between its first and second        positions, and reverse.    -   The shaft is provided with a paddle which lies on the downward        path of the pin between its first and second positions, when the        shaft is in its first angular position, and which is away from        the downward path, when the rotating shaft is in its second        angular position.    -   The paddle is secured to a first end of the shaft and the gas        cylinder is connected by a rocker arm to a second end, opposite        to the first end, of the shaft.    -   The honing machine includes elastic means for biasing the pin        downwardly.    -   The elastic means bias the pin against the paddle when the        rotating shaft is in its first angular position.    -   The elastic means is a coil spring mounted around the pin and        compressed between a lower surface of the work piece holder and        a peripheral shoulder of the pin.    -   The work piece is provided with a vertical through hole and the        pin is slidably movable inside the vertical through hole.    -   The pin has an upper head for receiving an outer surface of a        bearing ring, the concave surface of the work piece holder has a        stepped portion, which is below an exposed surface of an        adjacent pad and the upper head of the pin is accommodated above        the stepped portion of the upper surface of the work piece        holder and at a level below the upper surface of the adjacent        pad when the damper is in its second passive configuration.    -   The honing machine includes a transfer mechanism for feeding the        honing station with bearing rings, one after the other, the        transfer mechanism including a first transfer box, adapted to        accommodate a bearing ring and movable in translation, in a        to-and-fro movement with respect to the frame, along a first        axis, a second transfer box, adapted to accommodate a bearing        ring and movable in translation, in a to-and-fro movement with        respect to the frame, along a second axis parallel to the first        axis, first driving means for driving the first transfer box in        translation along the first axis and second driving means for        driving the second transfer box in translation along the second        axis, in such a way that the second transfer box is located        under and adjacent the first transfer box, above the honing        station, and that the second transfer box has a top inlet        opening which is vertically aligned with a bottom outlet opening        of the first transfer box.

The invention also concerns a method for feeding a honing station of ahoning machine as described here-above. Such a method includes at leastthe following steps consisting in:

-   -   a) setting the damper in its first active configuration    -   b) introducing the bearing ring by gravity into the honing        station up to a point where it contacts the damper    -   c) setting the damper in its second passive configuration

Moreover, when the damper of the honing machine includes a pin movablein translation along a vertical direction as mentioned here-above, itcan be provided that, during step c), an upper surface of the pin ismoved downwardly by gravity up to a level where it is below an uppersurface of an adjacent pad of the work piece holder.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood on the basis of the followingdescription which is given in correspondence with the annexed figuresand as an illustrative example, without restricting the object of theinvention. In the annexed figures:

FIG. 1 is a partial perspective view of a honing machine according tothe invention in a loading configuration;

FIG. 2 is a perspective view similar to FIG. 1, when the honing machineis in a honing configuration;

FIG. 3 is a perspective view of a first transfer box, which belongs to atransfer mechanism of the honing machine of FIG. 1;

FIG. 4 is a perspective view of a second transfer box, which belongs tothe same transfer mechanism;

FIG. 5 is a partial front view of the machine of FIGS. 1 and 2, wheresome parts are omitted, for the sake of clarity;

FIG. 6 is a front view similar to FIG. 5, at a smaller scale and wheresome side panels have been removed in order to show the bearing rings inthe transfer mechanism;

FIG. 7 is a front view similar to FIG. 6 where, for the sake of clarityonly two bearing rings are represented in the machine, which is in theconfiguration of FIGS. 5 and 6;

FIGS. 8, 9, 10, 11, 12, 13, and 14 are front views similar to FIG. 6when the transfer mechanism of the honing machine is in successiveconfigurations;

FIG. 15 is an enlarged detailed view of a work piece holder of themachine of FIGS. 1 to 14, when this work piece holder is in theconfiguration of FIG. 13;

FIG. 16 is a perspective view of the work piece holder in theconfiguration of FIG. 15;

FIG. 17 is an enlarged view, similar to FIG. 15 when the work pieceholder is in the configuration of FIG. 14;

FIG. 18 is a perspective view of the work piece holder in theconfiguration of FIG. 17, in a direction close to the one of FIG. 16;and

FIG. 19 is a perspective view of the work piece holder, in theconfiguration of FIGS. 17 and 18, in another direction.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The honing machine 2 represented on FIGS. 1 to 19 includes a base frame4 which supports a fixed pole 6. A honing stone 8 is supported by an arm10 which extends upwardly from fixed bracket 6.

Honing machine 2 also includes a movable frame 12 slidable, with respectto base frame 4, along a fixed longitudinal axis X4, in two oppositedirections, as shown by double arrow A1. A non-represented actuator,such as an electric motor or a pneumatic or hydraulic cylinder, drivesmovable frame 12 in translation along axis X4.

Movable frame 12 supports a honing station 14 where a bearing ring 100is held in position for interaction with the honing stone 8. Moreprecisely, movable frame 12 supports a rotary actuator, in the form ofan electric motor 16, which is adapted to drive bearing ring 100 presentin holding station 14 around a rotation axis X14 which is fixed withrespect to frame 12 and parallel to axis X4. Movable frame 12 supports aholding mechanism 17 provided with two rollers 172 adapted to come intocontact with a lateral surface of bearing ring and to push this ringtowards electric motor 16, in order to make a friction type connectionbetween bearing ring 100 and a rotating member 162 driven by motor 16 inrotation around axis X14. Actually, holding mechanism 17 is movable withrespect to frame 12, in translation along an axis X17 parallel to axesX4 and X14, between a loading configuration of honing machine 2represented on FIG. 1 and a honing configuration represented on FIG. 2.In the configuration of FIG. 1, rollers 172 do not contact bearing ring100 whereas, in the configuration of FIG. 2, rollers 172 push bearingring 100 against rotating member 162.

In the following description, unless otherwise specified, one considershoning machine 2 in its loading configuration. For the sake of clarity,items 4 to 10 and 17 are omitted on FIGS. 5 to 14.

Honing station 14 includes, amongst others, a work piece holder 18 whichhas a concave surface 182, with a section perpendicular to axis X14 inthe form of an arc of a circle centered on axis X14. This work pieceholder is selected in order to match the outer dimensions of bearingrings to be processed by honing machine 2. Thus, work piece holder isgenerally changed when a new type of bearing rings is to be processed inhoning machine 2.

Honing machine 2 also includes a transfer mechanism 20 which is used tosuccessively feed honing station 14 with bearing rings stored in aninlet chute 22.

Transfer mechanism 20 includes a first transfer box 202 and a secondtransfer box 204 which is located immediately below the first transferbox.

In the present description, the words “below”, “above”, “inferior” or“superior” relate to a working configuration of honing machine 2.“Above” or “superior” relates a surface or a part which is orientedtowards the top of machine 2 in such a configuration, whereas “below” or“inferior” relates to a surface or a part which is oriented to thebottom of this machine.

First transfer box 202 is visible alone on FIG. 3 and includes a firstmetallic side wall 2020 and a second metallic side wall 2022. Twospacers 2024 and 2026 made of a synthetic material are interposedbetween side walls 2020 and 2022, so that an inside volume V202 of firsttransfer box 202 is defined between side walls 2020 and 2022. Aninspection window 2028 is provided on side wall 2022 and allows checkingthe content of volume V202 through side wall 2022.

Spacer 2024 extends on the whole height of side walls 2020 and 2022 andprotrudes downwardly with respect to these two walls. Spacer 2026extends between lower parts of side walls 2020 and 2022, so that aninlet opening 202A is defined on the lateral side of box 202 visible onFIG. 2. This inlet opening 202A allows introduction of a bearing ringwithin volume V202. Moreover, an outlet bottom opening 202B is definedbetween the lower edges of side walls 2020 and 2022 and between spacers2024 and 2026.

Reference character 2026A denotes the upper surface of spacer 2026. Thisupper surface 2026A is inclined towards outlet opening 202B. In otherwords, this surface lowers in the direction of outlet opening 202B.

Reference characters 2024B and 2026B respectively denote the verticalsurfaces of spacers 2024 and 2026 which face each other. In thedirection of axis Y202, outlet opening 202B is defined between surfaces2024B and 2026B. Reference character D2 denotes the distance measuredbetween surfaces 2024B and 2026B along axis Y202.

Second transfer box 204 also includes two metallic side walls 2040 and2042 and two synthetic spacers 2044 and 2046. An inspection window 2048is provided in side wall 2042 and allows inspection of the inside volumeV204 of second transfer box 204. An inlet opening 204A of secondtransfer box 204 is defined between the top edges of side walls 2040 and2042. An outlet opening 204B of second transfer box 204 is definedbetween spacers 2044 and 2046, below the respective central portions ofthe lower edges of side walls 2040 and 2042.

Reference character 2046A denotes the upper surface of spacer 2046. Thissurface is horizontal.

Reference character 2046B denotes an end face of spacer 2046 orientedtowards spacer 2044. Outlet opening 204B is defined, along axis Y204,between spacer 2044 and end face 2046B.

In working configurations of transfer mechanism 20, inlet opening 204Ais vertically aligned with outlet opening 202B, so that a bearing ringcan go from volume V202 into inside volume V204 by gravity.

Transfer mechanism 20 also includes a first pneumatic cylinder 206mounted on frame 12 and adapted to drive first transfer box 202 intranslation along an axis Y202 which is horizontal and perpendicular toaxis X4. Double arrow A2 represents the to-and-fro movements of firsttransfer box 202 in the direction of axis Y202. Cylinder 206 is arodless cylinder whose output member is connected to first transfer box202.

A second pneumatic cylinder 208 is mounted on movable frame 12 and itsoutput member is connected to second transfer box 204 and drives thisbox in translation along a second axis Y204 which is parallel to axisY202. Double arrow A4 shows the to-and-fro movements of second transferbox 204 along axis Y204.

Honing machine 2 also includes an inlet chute 22 and an outlet chute 24.In machine 2, bearing rings go from inlet chute 22 to outlet chute 24via transfer mechanism 20 and honing station 14.

Outlet chute 24 is provided with a side wall 242 and an inductive sensor244 which allows detecting the presence of a bearing ring in an insidevolume V24 of chute 24, when the ring lies or rolls on a lower surface246 of outlet chute 24.

For the sake of clarity, side walls 2022, 2042 and 242 are omitted onFIGS. 6 to 14, in order to show inside volumes V202, V204 and V24 andtheir content.

An inlet gate 26 is arranged between inlet chute 22 and transfermechanism 20 and this inlet gate is controlled by a pneumatic cylinder28.

In this example, cylinders 206, 208 and 28 respectively form actuatorsfor items 202, 204 and 26. Alternatively, other types of actuators canbe used, for instance hydraulic cylinders, mechanical jacks or electricmotors.

As shown on FIGS. 15 to 19, work piece holder 18 is equipped with twopads 184 and 186 whose outer or exposed surfaces, respectively 184A and196A, slightly protrude with respect to concave surface 182, by a fewtenth of millimeters, so as to make sure that each bearing ring willtouch only the pads and thereby be accurately positioned. Pad 184 islocated in the lower part of honing station 14, below bearing ring 100present in this station. Pad 184 is substantially aligned, along avertical direction, with axis X14. Pad 186 is located on a side ofhoning station 14, actually on the same side as inlet chute 22, roughlyat the same height as axis X14. The shape of work piece holder 18, inparticular the radius of curvature of concave surface 182 and thelocation of pads 184 and 186 depend on the geometry of the bearing ringsto be processed in honing machine 2.

The exposed surface 184A or 186A of each pad 184 or 186 isadvantageously formed of a layer of polycrystalline diamond or “PCD”,which presents a high mechanical stiffness. This high stiffness layerhas a thickness between 1 and 500 μm and is applied on an armature 184Bor 86B made for instance of carbide, with a thickness between 0.1 and 10mm, preferably equal to about 0.2 mm. Alternatively, armature 184B or186B and the high stiffness layer can be made in other materials withsuitable mechanical properties to resist wear, shocks and lower thevariation of dimensions with temperature and time. On FIGS. 15 and 17,the thickness of the high stiffness layers forming surfaces 184A and186A is exaggerated, in order to show these layers more easily.

A through hole 188 is provided on work piece holder 18 and extendsvertically and downwardly from a stepped portion 182A of concave surface182. Through hole 188 is visible on FIG. 15 via a local cutaway of workpiece holder 18, which is metallic.

Z188 denotes the central axis of through hole 188. A metallic pin 190 isslidably mounted within through hole 188 and movable along axis Z188between a first position, represented on FIGS. 15 and 16, and a secondposition, represented on FIGS. 17 to 19. Pin 190 has an upper head 192with an upper surface 192A adapted to be in contact with a lower portionof the outer radial surface of bearing ring 100 present in honingstation 14, as explained here-under. Pin 190 also has a lower sole 194which defines a peripheral shoulder 196 around the main portion of pin190. A coil spring 280 is mounted around pin 190, between shoulder 196and a lower surface 183 of work piece holder 18.

As shown on FIGS. 15 and 16, when pin 190 is in its first position, itshead 192 protrudes upwardly with respect to surface 184A of pad 184.Thus, head 192 of pin 190 is on the path of a bearing ring fallingtowards work piece holder 18. As shown on FIGS. 17 to 19, when pin 190is in its second position, upper surface 192A of head 192 does notprotrude above surface 184A. In this position, surface 192A is slightlybelow surface 184A, so that a bearing ring lying on work piece holder 18does not contact pin 190. In other words, in this second position, pin190 is out of reach of a ring present in honing station 14.

A shaft 30 is mounted on movable frame 12 next to work piece holder 18and its longitudinal axis Y30 is parallel to axes Y202 and Y204.Actually, shaft 30 is rotatably supported by movable frame 12, so thatit can rotate around axis Y30 between a first position, represented onFIGS. 15 and 16, and a second position, represented on FIGS. 17 to 19.

A first end 302 of shaft 30 is equipped with a paddle 304 which extendsradially with respect to axis Y30, so that it is located directly belowsole 194 in the configuration of FIGS. 15 and 16. More precisely, inthis configuration, sole 194 lies against an upper surface 306 of paddle304.

The second end 308 of shaft 30, which is opposite to first end 302, isconnected to a rocker arm 310. The end of rocker arm 310 opposite toshaft 30 is connected to an output rod 320 of a gas cylinder 32. Thus,gas cylinder 32 forms an actuator which allows pivoting shaft 30, inrotation around axis Y30, between the position of FIGS. 15 and 16, onthe one hand, and the position of FIGS. 17 to 19, on the other hand. Gascylinder 32 can also be used to dampen a rotation movement of shaft 30around axis Y30, in the direction of arrow R1 on FIG. 16, as explainedhere-below.

A non-represented pneumatic control unit is connected to cylinders 206,208, 28 and 32 and pilots these actuators, according to a predeterminedsequence, which is explained here-below.

Feeding of honing station 14 is now explained in connection to FIGS. 5to 19.

On these figures, a bearing ring present in honing station 14 isreferenced 100, whereas a bearing ring to be fed to honing station 14 isreferenced 102. FIG. 6 shows two bearing rings 102 in transfer mechanism20 but, for the sake of clarity, only one bearing ring 102 isrepresented on FIGS. 7 to 14. The configuration of honing machine 2 isthe same on FIGS. 6 and 7. In this configuration, bearing ring 100 ispresent in honing station 14 and centered on axis X14, in front ofrotary member 162. Inlet gate 26 has been opened by cylinder 28 andbearing ring 102 enters inside volume V202 of first transfer box 202 viainlet opening 202A. In this configuration, bearing ring 102 rolls onupper surface 2026A of spacer 2026 and falls within inside volume V204of second transfer box 204 via outlet opening 202B of box 202 and inletopening 204A of box 204. In other words, and as shown by arrow A7 onFIG. 7 and by the comparison of FIGS. 7 and 8, bearing ring 102 goes, bygravity, from inside volume V202 into inside volume V204.

Thus, inside volume V202 of first transfer box 202 accommodates bearingring 102 until it falls down into inside volume V204 of second transferbox 204. In the configuration of FIG. 8, and actually also in theconfiguration of FIGS. 9 to 12, volume V204 accommodates most of bearingring 102, but a top part of the ring remains in volume V202.

In the configuration of FIG. 8, bearing ring 102 is blocked withinvolume V204, and actually protrudes upwardly into volume V202 since ring102 lies on the upper surface 2046A of spacer 2046. Thus, space 2046works as a platform for supporting bearing ring 102 within volume V204.Moreover, ring 102 is located, along axis Y202, between spacers 2024 and2026. More precisely, transfer box 202 is designed so that distance D2is slightly larger than the outside diameter of ring 102. Thus, in theconfiguration of FIG. 8, ring 102 is guided between vertical surfaces2024B and 2026B. In this configuration, bearing ring 102 does notinterfere with bearing ring 100 because the opening defined betweenspacers 2024 and 2046 is not large enough for ring 102 to movedownwardly by gravity.

From the configuration of FIG. 8, second transfer box 204 is moved alongaxis Y204 by cylinder 208, in the direction of arrows A8 and A9 on FIGS.8 and 9, so that it reaches the position of FIG. 9. In this position ofsecond transfer box 204, its bottom outlet opening 204B is laterallyoffset from honing station 14.

Due to the movement of second transfer box 204 between the configurationof FIG. 8 and the configuration of FIG. 9, bearing ring 100 is ejectedfrom honing station 14 by the end face 2046B of spacer 2046. Then, ring200 falls within the inside volume V24 of outlet chute 24. During themovement of second transfer box 204 in the direction of arrows A8 andA9, bearing ring 102 rolls on upper surface 2046A of platform or spacer2046.

Cylinder 206 is piloted in a next step in order to move first transferbox 202 along axis Y202 in the same direction as second transfer box 204has been moved previously, as shown by arrow A10 on FIG. 10. Because ofthe translation movement of first transfer box 202, spacer 2026 works asa pusher for pushing bearing ring 102 in the same direction, towardsspacer 2044, within inside volume V204 and along axis Y204. On thisoccasion, bearing ring 102 rolls on surface 2046A. This movement offirst transfer box 202 goes on up to a point where outlet opening 202Bis vertically aligned with honing station 14, along a vertical axis Z14which crosses axis X14, as shown on FIGS. 10 and 11. This movement offirst transfer box 202 results in moving bearing ring 102 towards bottomoutlet opening 204B.

The platform formed by spacer 2046 temporary holds bearing ring 102within inside volume V204, from the configuration of FIG. 8 to theconfiguration of FIG. 11.

As shown on FIGS. 10 and 11, bearing ring 100 rolls on surface 246within chute 24 and passes in front of inductive sensor 244, so that theejection of bearing ring 100 from rolling station 14 is automaticallydetected.

Once this detection has occurred, it is sure that no bearing ringremains in honing station 14, so that this honing station can be loadedagain with bearing ring 102. To this end, second transfer box 204 ismoved along axis Y204 in the opposite direction, as shown by arrow A12on FIG. 2 that is in a direction opposite to the movement of firsttransfer box 202 in the previous step. This brings transfer mechanism 20in a configuration where outlet openings 202A and 204A of first andsecond transfer boxes 202 and 204 are vertically aligned, along verticalaxis Z14, with honing station 14. This is the configuration representedon FIG. 12.

From this configuration and because of gravity, ring 102 falls intohoning station 14, as shown by arrow A13 on FIGS. 12 and 13. In otherwords, bearing ring 102 follows a vertical downward path or trajectory,from volume V204 to honing station 14, this path being shown by arrowA13 on FIGS. 12 and 13.

The downward movement of ring 10 is dampened by pin 190, which protrudesupwardly from pad 184 on the downward path of bearing ring 102, sincework piece holder 18 is in the configuration of FIGS. 15 and 16. Whenbearing ring 102 reaches head 192 of pin 190, it exerts a downwardeffort E102, as represented on FIGS. 15 and 16, which is transmitted bypin 190 to paddle 304 and tends to rotate shaft 30 around axis Y30, inthe direction of rotation arrow R1. This rotation movement of shaft 30around its longitudinal axis is transmitted by rocker arm 310 to rod 320of gas cylinder 32. In other words, effort E102 is transmitted as apulling effort E′102 on rod 32, this pulling effort being dampened orslowed by the gas pressure within cylinder 32. Thus, shaft 30 and gascylinder 32 work as braking means for pin 190, when it goes from itsposition of FIGS. 15 and 16 to a lower position.

Once this dampening or braking effect of the downward movement of ring102 has been obtained with the damper formed of pin 190, shaft 30 andcylinder 32, cylinder 32 is actuated to push rod 320 outwardly, so thatrocker arm 310 and shaft 30 are brought into the configuration of FIGS.16 to 19 where paddle 304 is offset from pin 190. In other words, shaft30 is brought by gas cylinder 32 and rocket arm 310 from a first angularposition with respect to axis Y30 to a second angular position. In thefirst angular position of shaft 30, paddle 304 is in contact with sole194, so that paddle 304 interacts with the downward movement of pin 190going from its first position to its second position. More precisely,when shaft 30 is in its first angular position, paddle 304 lies on thedownward vertical path of sole 194 when pin 190 moves from its firstposition to its second position. Because of the biasing effort of spring280, sole 194 is in contact with paddle 304 as long as shaft 30 remainsin its first angular position. In the second angular position of shaft30, paddle 304 is out of reach of sole 194, so that shaft 30 does notinteract with pin 190 which is only subjected to its weight and to theaction of spring 280. Thus, pin 190 automatically reaches its secondposition where surface 192A is below surface 184A. Spring 280 pushessole 194 away from surface 183, so that head 192 comes into contact withsurface portion 182A, to the point that head 192 does not protrudeupwardly with respect to surface 184A of pad 184, as explainedhere-above.

Then ring 102 reaches the configuration of FIG. 14 where it is centeredon axis X14 within honing station 14. In this configuration, centeringof ring 102 with respect to axis X14 is obtained via pads 184 and 186which are precisely positioned with respect to frame 12 and canwithstand a large number of operations because of their structuralhardness.

In other words, thanks to the use of pin 190, shaft 30 and gas cylinder32, it is possible to use high resistance pads 184 and 186, without riskof breaking pads 184 or 186 or caulking the outer radial surface of ring102.

In the configuration of FIG. 14, ring 102 is ready for being pushed byholding mechanism 17 against rotating member 162, so that it can bedriven in rotation around axis X14 by electric motor 16 once movableframe 12 has been moved along axis X4 in order to align, along axis X4,the inner radial surface of ring 102, now present in honing station 14,with honing stone 8.

At a later stage, which corresponds to the configuration of FIG. 11,that is when a bearing ring has just been ejected from honing station14, gas cylinder 32 actuates rocker arm 310 to bring shaft 30 back toits first position, which brings pin 190 back to its position of FIGS.12 to 16.

Throughout the process described here-above, inspection windows 2028 and2048 allow checking the position of bearing ring 102 in transfermechanism 20.

1. A honing machine for bearing rings, this machine including: a frame;a honing tool; a honing station for holding a bearing ring in positionwith respect to the honing tool, the honing station including a workpiece holder with a concave surface equipped with at least one pad forsupporting a bearing ring; and a damper, the damper being movablebetween a first active configuration and a second passive configuration,where, in the first active configuration, the damper protrudes on a pathof a bearing ring moving towards the work piece holder in the honingstation, where, in the second active configuration, the damper is out ofreach of a bearing ring in the honing station.
 2. The honing machineaccording to claim 1, wherein each pad of the work piece holder iscoated with a high stiffness material, in particular with a layer ofpolycrystalline diamond.
 3. The honing machine according to claim 1,wherein each pad of the work piece holder is coated with a layer ofpolycrystalline diamond.
 4. The honing machine according to claim 1, thedamper further including a pin and a damping feature, wherein the pin ismovable in translation along a vertical axis, wherein the dampingcomponent is adapted for braking a vertical downward displacement of thepin.
 5. The honing machine according to claim 4, the work piece furthercomprising a vertical through hole, wherein the pin is slidably movableinside the vertical through hole.
 6. The honing machine according toclaim 4, the pin further comprising an upper head, wherein the upperhead is adapted to receive an outer surface of a bearing ring; and theconcave surface of the work piece holder further comprising a steppedportion, wherein the stepped portion is located below an exposed surfaceof an adjacent pad; wherein the upper head of the pin is accommodatedabove the stepped portion of the upper surface of the work piece holderand at a level below the upper surface of the adjacent pad, when thedamper is in its second passive configuration.
 7. The honing machineaccording to claim 4, wherein the pin is movable along the vertical axisbetween a first position and a second position, wherein, in the firstposition, the pin protrudes upwardly with respect to an adjacent pad ofthe work piece holder, wherein, in the second position, an upper surfaceof the pin is positioned below an upper surface of the adjacent pad. 8.The honing machine according to claim 7, the damping feature furtherincluding: a rotatable shaft movable in rotation around its longitudinalaxis, between a first angular position where it interacts with avertical downward movement of the pin, between its first and secondpositions, and a second angular position where the shaft is out of reachof the pin; and a gas cylinder for moving the shaft between a firstposition of the shaft and a second position of the shaft, and reverse.9. The honing machine according to claim 8, the shaft further comprisinga paddle, wherein the paddle lies on the downward path of the pinbetween a first position of the paddle and a second position of thepaddle, when the shaft is in a first shaft angular position, and whichis away from the downward path, when the rotating shaft is in its secondangular position.
 10. The honing machine according to claim 9, whereinthe paddle is secured to a first end of the shaft and the gas cylinderis connected by a rocker arm to a second end, opposite to the first end,of the shaft.
 11. The honing machine according to claim 8, furthercomprising an elastic element for biasing the pin downwardly.
 12. Thehoning machine according to claim 11, wherein the elastic element biasesthe pin against the paddle when the rotating shaft is in its firstangular position.
 13. The honing machine according to claim 11, whereinthe elastic element is a coil spring, wherein the coil spring is mountedaround the pin and compressed between a lower surface of the work pieceholder and a peripheral shoulder of the pin.
 14. The honing machineaccording to claim 1, further comprising a transfer mechanism forfeeding the honing station with bearing rings, one after the other, thetransfer mechanism including: a first transfer box, adapted toaccommodate a bearing ring and movable in translation, in a to-and-fromovement with respect to the frame, along a first axis, the firsttransfer box including a bottom outlet opening, a second transfer box,adapted to accommodate a bearing ring and movable in translation, in ato-and-fro movement with respect to the frame, along a second axis, thesecond axis being parallel to the first axis, the second transfer boxincluding a top inlet opening, a first driving mechanism for driving thefirst transfer box in translation along the first axis and a seconddriving mechanism for driving the second transfer box in translationalong the axis direction, wherein the second transfer box is locatedunder and adjacent the first transfer box, above the honing station, andthat the second transfer box has a top inlet opening which is verticallyaligned with a bottom outlet opening of the first transfer box.
 15. Amethod for feeding a honing station of a honing machine with a bearingring, the honing machine comprising: a frame; a honing tool; a honingstation for holding a bearing ring in position with respect to thehoning tool, the honing station including a work piece holder with aconcave surface equipped with at least one pad for supporting a bearingring; and a damper, the damper being movable between a first activeconfiguration and a second passive configuration, wherein, in the firstactive configuration, the damper protrudes on a path of a bearing ringmoving towards the work piece holder in the honing station, wherein, inthe second active configuration, the damper is out of reach of a bearingring in the honing station, the method comprising steps of: a) settingthe damper in a damper first active configuration; b) introducing thebearing ring by gravity into the honing station up to a point where thebearing ring contacts the damper; and c) setting the damper in itssecond passive configuration.
 16. The method according to claim 15, thedamper further including a pin and a damping feature, wherein the pin ismovable in translation along a vertical axis, wherein the dampingcomponent is adapted for braking a vertical downward displacement of thepin, during the step of setting the damper in its second passiveconfiguration, the method further comprising a step of moving an upperportion of the pin downwardly by gravity up to a level where it is belowan exposed surface of an adjacent pad of the work piece holder.